Removable disks included in protective cartridges have been available for some time. Generally, the protective cartridges include either a flexible disk or a relatively rigid disk. Typical flexible disk cartridges as shown in U.S. Pat. Nos. 4,445,155 to Takahashi, et al.; 4,445,157 to Takahashi; 4,546,397 to Asami, et al; 4,573,093 to Obama, et al; and 4,675,758 to Tanaka. Rigid disk cartridges are shown in U.S. Pat. Nos. 4,488,187 to Alaimo; 4,503,474 to Nigam; 4,504,879 to Toldi, et al.; 4,683,506 to Toldi, et al.; 4,717,981 to Nigam, et al; 4,722,012 to Toldi, et al.; 4,864,452 to Thompson, et al.; 4,870,518 to Thompson, et al.; 4,864,437 to Couse, et al.; 4,920,462 to Couse, et al.; 4,965,685 to Thompson, et al.; and 4,965,691 to Iftikar, et al. Although optical disks are possible, usually such flexible (floppy) and rigid (hard) disks are coated with suitable magnetic media, for writing data and reading data therefrom. Each disk is surrounded by a housing designed to prevent contamination or damage to the magnetic media of the disk. Some floppy disk cartridges just have a window to allow access, but for a rigid or hard disk cartridge, the housing must have an access shutter or other type of door to prevent contamination or damage. The shutter is opened when the cartridge is inserted into a disk drive mechanism, to allow the read/write heads access to the disk, and closed when the cartridge is ejected. The heads move in and out linearly or arcuately across the disk. In floppy disk drives, the heads are designed to lightly touch the magnetic media. In hard disk drives, the heads float on a thin layer of air so they never touch the disk while it is spinning. Because of the head contact, floppy disks tend to wear out after a short time and the drives occasionally need their heads cleaned, while hard disks can last the lifetime of the computer to which they are connected. In hard disk drives, environmental contamination may be reduced by providing seals about the access shutter and adjacent a hub used to spin the disk.
Generally, the requirements for a disk cartridge are: protect the disk from damage and contamination, provide access for the read/write heads on both sides of the contained disk, provide access for drive means to spin the disk, provide rigidity sufficient to assure that normal stresses do not cause the housing to bend and come into contact with the disk, provide means to control movement of the disk within the cartridge when the cartridge is outside its drive, and do all of this in minimum volume. In addition, some sort of mechanism is usually provided to retain the shutter closed except when the cartridge is in the relative clean and safe environment within a disk drive. Cartridges typical of those available in the prior art are disclosed in U.S. Pat. Nos. 4,864,452 and 4,503,474. The cartridge arrangement shown in the '474 patent is for use with a disk drive containing heads that are movable in relationship to the disk by means of a linear device, such as a stepper motor or a linear voice coil motor, which are generally expensive and not particularly versatile or fast. The cartridge shown in the ' 452 patent is for use with a radial arm voice coil actuator, which is economical and efficient, but requires a larger opening and is more difficult to align from drive to drive.
The housings of hard disk cartridges usually are constructed from plastic material, which must be relatively thick to withstand day-to-day abuse. The housing also must be relatively thick to support a shutter and to allow the insertion of the read/write heads within the sides thereof. The shutter of such a housing usually opens an edge because enough structural support cannot be provided to allow a corner to be missing. The resulting cartridges are bulky, heavy and have dimensions which are too big to fit into a shirt pocket.
Modern floppy disk drives merely require insertion of a cartridge through a slot and springs and linkages within the drive thereafter properly position the cartridge in the drive. In some instances, a knob or button must be manipulated to connect a rotational drive motor to the disk and to bring the heads into contact with the magnetic media. Removable cartridge hard disk drives use similar linkages and also motors and solenoids, but usually require the manipulation of a lever to seat and eject the cartridge. The motors and solenoids use electrical power, and cause excessive current drain that is undesirable for battery powered laptop and notebook personal computers.
Therefore, there has been a need to provide a disk drive with a removable cartridge which is small and thin, is capable of operating quickly at extremely high data densities, which uses almost no electrical power for cartridge insertion and ejection, which is rugged and relatively immune to physical damage, and can reliably establish a mechanical interface between the disk within the cartridge and the disk drive no matter what the orientation of the cartridge with respect to gravity without requiring a complex series of manual manipulations.